The present invention relates to electric motors generally and, more particularly, but not by way of limitation, to a novel electric motor which provides both linear and/or rotary motion at a single output shaft.
In certain applications, it is desirable to have a shaft which may selectively rotate and/or reciprocate. Such an application, for example, is in the robotic picking and placing of components where it may be required to axially move a component to an insertion position and then rotate the component to screw it in place. Conventional motor arrangements are often complicated and heavy, a substantial disadvantage for robotics applications. Another type of application requiring a shaft which may selectively rotate and/or reciprocate is in the precise control of laparoscopic and other such medical instruments.
In either type of application, it is frequently required that the linear motion be locked while rotary motion takes place. For a rotary/linear motor, this makes it desirable that the linear and rotary motions be controllable independently of one another.
A problem with motors having linear motion is that the motors frequently provide inadequate output shaft support when heavy side loads are imposed on the output shafts thereof.
Accordingly, it is a principal object of the present invention to provide an electric motor which provides both linear and/or rotary motion at a single output shaft.
It is an additional object of the invention to provide such an electric motor in which linear and rotary motions are controllable independently of one another.
It is a further object of the invention to provide such a motor that is simple and economical to manufacture.
An additional object of the invention is to provide such a motor that is lightweight and compact.
Other objects of the present invention, as well as particular features, elements, and advantages thereof, will be elucidated in, or be apparent from, the following description and the accompanying drawing figures.
The present invention achieves the above objects, among others, by providing, in a preferred embodiment, a linear/rotary motor, comprising: first and second stator structures, having magnetically coupled thereto, respectively, first and second rotors; a first, externally threaded shaft fixedly attached to said first rotor and extending axially therefrom, such that rotation of said first rotor causes rotation of said first, externally threaded shaft; a second shaft, having a splined external surface, extending through a complementarily shaped opening defined through said second rotor, and axially movable with respect thereto, such that rotation of said second rotor causes rotation of said second shaft; and said second shaft including threaded means cooperatively engaging said first, externally threaded shaft, such that rotation of said first, threaded shaft can cause linear motion of said second, cylindrical shaft. Said motor can be operated to provide rotary, linear, or simultaneous rotary and linear motion of said second shaft.